Rectifier circuits convert alternating-current (AC) into direct-current (DC). For example, some rectifier circuits include a diode circuit that is configured to function as a rectifying element by conducting alternating half-cycles of an AC input signal. Such rectifiers may be limited in switching speed by total capacitance therein. The efficiency of such rectifier circuits can be limited by the threshold forward voltage (about 0.3 V) for the rectifier circuits to become conductive. For high current applications, the threshold forward voltages of the diodes may result in an unacceptable heat generation.